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Subject: Re: Triple Filter: who needs it?!?!?

From: "Paul Schreiber" <synth1@...
Date: 1999-03-12

Just remember Mark is the US rep for Nord Modulars!! The EVIL EMPIRE!!!!

The demo files do show the differences really well.

Paul S.

-----Original Message-----
From: Dave Bradley <daveb@...>
To: <>
Date: Friday, March 12, 1999 8:05 AM
Subject: [motm] Re: Triple Filter: who needs it?!?!?

>From: "Dave Bradley" <daveb@...>
>I believe I posted this before, the first time I proposed this filter. The
>url below on Mark Pulver's site has a good review of the MAM filter, a nice
>block diagram, AND 2 really nice RealAudio samples of a dry string patch,
>and the same patch through the filter. Also some background info on
>Vactrols. This will help you answer the question "who needs it".
>Now that we've been talking about this filter for awhile, go check it out
>you haven't already. It's neato!
>Dave Bradley
>Principal Software Engineer
>Engineering Animation, Inc.
>> -----Original Message-----
>> From: Paul Schreiber [mailto:synth1@...]
>> Sent: Thursday, March 11, 1999 9:09 PM
>> To:
>> Subject: [motm] Triple Filter: who needs it?!?!?
>> From: "Paul Schreiber" <synth1@...>
>> This filter is a klone of the Korg PS3100 synth's filter. It is
>> also a klone
>> of the MAM filter box (made in Germany) which is a stereo version
>> (hence Dave stereo remark).
>> This filter (like the Moog filter in it's own way) is good for 1
>> sound, but
>> ∗BOY∗ what a sound!
>> It makes the most W O N D E R F U L string and ambient pads you've ever
>> heard!!
>> The best demo I can offer is buy either "Equinox" or "Oxygene" by Jean
>> Michael Jarre.
>> The "swooshing" string sound is a Korg PS3100 (he also uses an
>> old EH Small
>> Stone phaser)
>> The "smoothness" of the effect is because the filter is not really a
>> traditional VCF. Rather, it is
>> a filter that we "wiggle" the cutoff pots with a special device called a
>> Vactrol.
>> A Vactrol is a LED touching a cadmium-sulfide photocell. This
>> resistance of
>> the photocell varies as the
>> LED intensity. The range of resistance is like 1K-100K. The Vactrol is
>> size of a sugar cube.
>> Now, the "badness" of the photocell is that is is S L O W
>> to react
>> to changes in the light from the LED.
>> This means the filter sorts of drags behind the LED, trying to play
>> up". This effect causes the filters
>> to "slur" and "smear" when the control voltages changes slope.
>> Like......the
>> peaks of a triangle wave.
>> It's sort of like pulling a toy car with a Slinky.
>> This "badness" of Vactrols is used in 95% of all audio compressors.
>> Including the $2300 Joe Meek box.
>> So, for $13 buy a JM Jarre CD and check it out! (plus, they are damn fine
>> CDs. I play them all the time)
>> Paul S.
>> ------------------------------------------------------------------------
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